baya weavers nesting

Posted by on 04 Sep 2016

It is nesting season for the baya weavers!

Baya weaver birds are small, sparrow-size birds which resemble the sparrows during the non-breeding season. During May-June, as the breeding season approaches, their gonads (sexual glands) become active and the adult males develop yellow and black color plumage on head, breast and throat; and their bills also darken. By the time the monsoon starts, the males are in bright yellow summer colors, and ready for breeding through the monsoon season (June-September).

baya weaver nest building

Why do they breed during the summer monsoon? Obviously, the grass is green during this side of the monsoon! Baya weavers forage in flocks for seeds on wild grass like these below, which are plenty after the monsoon rains. This is also the time when insects are plenty, especially to feed their young. How many bayas can you count in the image below?!

a group of baya weaver birds feeding on grass seeds

Nesting success? Baya weaver nests are exclusively built by the males and then displayed to the females. What are the factors on which the female makes it selection? Among birds, elaborate nests and decorations built by males may help females to assess a male’s quality. One of the most popular architectural attributes of the weaver nest is the entrance tube, which can get as long as 90 cm. Female birds are also selective in choosing nests which provides safety (in terms of nest height and location). So what does the baya weaver base their selection on? Is it the architecture or the location?

baya weaver nest building at Pune, Maharashtra

Safer on thorny trees: Observation shows that the female weavers are inclined towards nests which are safely located in thorny trees, farther away from the trunk and situated high above the ground. Thornless trees have higher rates of snake predation than thorny trees. Nesting success also increases with with thickness of the supporting branch and for nests which are woven with fine fiber.  Thick branches may stabilize nests during strong monsoon winds, and may also be less likely to break.

baya weaver and a garden lizard against the blue sky

Despite these precautions, garden lizards like the one above, and tree mouse do occasionally raid these nests.

Some history: Baya weavers and their unique nesting nature were first recorded in Ain-i-Akbari, the 16th-century document recording the administration of Akbar’s empire, and which is part of the a much larger document, the Akbarnama. The Volume III translation by Colonel H. S. Jarret talks about wild/domesticated bayas: “The baya is like a wild sparrow but yellow. It is extremely intelligent, obedient and docile. It will take small coins from the hand and bring them to its master, and will come to a call from a long distance. Its nests are so ingeniously constructed as to defy the rivalry of clever artificers.”

Species: Ploceus philippinus
English: Baya weaver
Location: IITM colony, Pune, Maharashtra
Date: 3 Sep 2016

References:
1. Balasubramanian, K. S., & Saxena, R. N. (1973). Effect of pinealectomy and photoperiodism in the reproduction of Indian weaver birds, Ploceus philippinus. Journal of Experimental Zoology, 185(3), 333-340.
2. Fazl, A., & Jarrett, H. S. (1983). The Ain-i-Akbari:. Royal Asiatic Society of Bengal. (No. 61).

3. Quader, S. (2006). What makes a good nest? Benefits of nest choice to female Baya Weavers (Ploceus philippinus). The Auk, 123(2), 475-486.

Indian Grey Hornbill—the seed dispersers

Posted by on 07 Aug 2016

There are about 54 species of hornbills in the world, out of which 9 occur in India. The hornbill pictured here is the Indian Grey Hornbill, which is common across the Indian subcontinent, except the wettest (Western Ghats and northeast) and the driest (northwest) parts of the country.

Indian Grey Hornbill, Ocyceros birostris at Pune, Maharashtra

Breeding/Nesting
Hornbills have unique breeding habits, where the female confines herself into a nest cavity in a tree, with only a narrow opening through which the male shares the food throughout the nesting period. For the Indian grey hornbills, the total nesting period is about 87 days, where the female is confined to the nest cavity for an average of 76 days. Most of the grey hornbill nests are in hollows of the Mahagony tree family, located nearby riverine habitats. Deforestation, agriculture and other developmental activities have restricted the range of many species like these hornbills.

Grey hornbills as seed dispersers
Hornbills play a key role in seed dissemination, germination and regeneration of trees. This is because they are mainly frugivores (fruit consuming) and can break up/swallow large fruits, and regurgitate the seeds without damaging, making them the perfect dispersers. Since they travel long distances in search of fruits, they are capable of moving these seeds to distant locations.

Grey hornbills are effective seed dispersers for trees such as Premna tomentosa (a teak like tree), Putranjiva, Fern trees and even Sandalwood trees! Many of these are medicinally and commercially valuable trees but they generate very few seeds and propagation depends on birds like these hornbills.

Mid-air play and fight
Like many other hornbills, the grey hornbill has a long curved bill, which has a casque (helmet) on the top. The male hornbills engage in midair clashes where they jar against each other’s casques to establish their dominance and as part of their social play. This behaviour is known as aerial jousting.

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olive ridley turtles—and dinosaurs

Posted by on 27 Mar 2016

Watching these Olive Ridley turtle hatchlings making their first steps to the sea is an emotional experience!

Olive Ridley Turtle hatchling, Velas, Maharashtra

Olive Ridley turtles are among the five species of marine turtles which are known to inhabit Indian coastal waters and islands. Odisha on the eastern coast of India hosts one of the largest mass nestings (known as arribadas) of these turtles, supporting a nesting population of probably more than half a million.

There are Olive Ridley turtle populations elsewhere in the Indian Ocean too, scattered around from Sri Lanka to Kerala to Pakistan on the west coast. We went to one of these nesting sites or “rookeries”, snuggled amid a laid-back village called Velas, on the coast of Maharashtra. While half a million turtles nest on the Odisha coast, only a few hundreds visit the Maharashtra coast. Conserving these few turtles are important as they are critically endangered species.

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blue marsh hawk and the skimmers

Posted by on 12 Jun 2014

The blue marsh hawk belong to the dragonfly family of skimmers, and are conspicuous with their blue thorax and tail.

blue marsh hawk,  orthetrum glaucaum

Dragonflies, especially the males of some species, are also territorial in nature. Research shows that among some marsh skimmers, the males with longer hind wings have an upper hand in winning territorial conflicts.

Species: orthetrum glaucaumFamily: libellulidae

Here are a few other skimmers from our earlier articles:

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the veiled lady

Posted by on 29 May 2014

A pretty damsel adorning a bridal veil.

the veiled lady fungi

The veiled lady, or the bridal veil stinkhorn as it is popularly known, belongs to the fungi family of stinkhorns. A mature stinkhorn has a phallic structure which is about 10-15cm high and with a cap on top, skirted with a net/membrane (indusium), and hence its scientific name, phallus indusiatus. The veiled lady mushroom is edible, and enjoys an elite status for its medicinal and aphrodisiac properties. Indeed, an obscure study states that the smell emanating from these mushrooms can trigger spontaneous orgasms in human females!

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